1. Field of the Invention
The present invention relates to a method and apparatus for measuring flow rates of viscous fluids, and has particular, although not exclusive, utility in measuring the flow of heavy crudes from oil wells.
In various oil producing fields throughout the world the crude being extracted from the earth is highly viscous. Several deposits in Kern County, California are exemplary. As a consequence, the power requirements for pumping the crude, the use of steaming techniques, and the ability to accurately measure fluid flow may make such wells marginal in value, depending upon current price levels for crude. In order to determine whether a well is productive or not, it is imperative that the operator be able to measure its output, which may be as low as one to five barrels a day, and which translates, at the lower end, into less than 0.02 of a gallon a minute.
Accordingly, it is a primary objective of the present invention to provide apparatus for measuring, accurately, the flow from heavy crude wells.
It is yet another objective of the present invention to be able to use such apparatus for measurement of several wells, selectively, sequentially, and to take several timed measurements on each well.
2. Overview of the Prior Art
Flow measuring devices currently in use have the capability of accurately measuring fluid flows as low as nine gallons a minute. Below that flow rate, however, accurate measurement of viscous fluids such as heavy crude is virtually nonexistent, at least insofar as field applications are concerned.
Flow measuring devices are, of course, not unheard of, Flint U.S. Pat. No. 672,935, having disclosed such a device as early as 1901. The essence of that patent, however, was an apparatus for protecting gas meters against inordinately high flow, as distinguished from low flow, as is the present case. Other measuring and pressure control devices are disclosed in Goldkamp U.S. Pat. No. 2,115,259 and Thieme U.S. Pat. No. 3,593,575. Finally, Holzum U.S. Pat. No. 4,193,299 suggests a device for controlling fuel flow for an internal combustion engine, but does not deal with viscous fluids such as heavy crude.
In point of fact, there simply is not a device, currently in use, which will accurately measure the flow of viscous fluids at flow rates in the range of 0.1 gallons per minute and above until the advent of the present invention.